(1) Field of the Invention
This invention relates to highly pure squalane from shark-liver oil, which squalane is excellent in stability and scarcely contains pristane being stimulative to the skin. The invention further relates to the raw material of medical, pharmaceutical and cosmetic products using the same and a method for preparing the same.
(2) Prior Art
The squalane is represented by the following structural formula. It is excellent in the adaptivity to living bodies, good spreading property and safety in use, so that it is widely used for preparing almost all of cosmetics such as several kinds of creams, especially nutrient cream and medicated creams, milky lotion, toilet lotion, lipstick, foundation, and face powder. In addition, it is used as a fatting agent for high quality soap, and also used for producing medical and pharmaceutical preparations such as ointment, suppository and medically lubricating agent. ##STR1##
Furthermore, owing to its advantageous properties, it is used as a fiber treating agent, leather surface modifying agent, sizing agent, and face wiping cloth. Still further, in view of its good durability at low temperatures and at high temperatures, it is also used as a lubricating oil for engines and so forth.
As described above, squalane is often used for various purposes. However, it sometimes comes into question when it is brought into contact with the skin, for example, in cosmetics and medical agents, because the pristane which is contained in squalane prepared from shark-liver oil, is stimulative to the skin.
The pristane (2,6,10,14-tetramethylpentadecane) is a saturated hydrocarbon which is represented by a molecular formula of C.sub.19 H.sub.40, and which is contained in animal oil or fat such as deep-sea shark-liver oil or else. The terms fat and oil are distinguished by their physical state. The fat is solid at ambient temperature, where the oil is liquid.
In the conventional art, the content of pristane in the commercially available squalane prepared from shark-liver oil is about 1,000 to 2,000 wt ppm.
The art to prepare squalane which does not contain pristane is disclosed in Japanese Laid-Open Patent Publication No. Hei 7-309785. This method was developed for the preparation of squalane from vegetable oils containing no pristane. Of course, this method cannot be applied to the treatment of animal oil.
The production of squalane from vegetable is small. In addition, the content of squalene as a raw material for squalane is also small, so that many processes are required for separation and concentration so as to obtain squalene. Furthermore, after the production of squalene, much waste must be discarded which causes the problem in environmental pollution.
It is considered that the anxiety to cause the disorder with the stimulation to the skin may be practically small when the quantity of pristane is so small as in the ordinary squalane prepared from shark-liver oil. However, the trend to demand a possibly safe product is increasing in recent years.
Accordingly, it is demanded to prepare squalene scarcely containing pristane from shark-liver oil as a raw material.
It is pointed out in recent years that silicone oil which is usually employed as a lubricant for condoms, is injurious to the human health. As a substitute for the silicone oil, the use of squalane is proposed in Japanese Laid-Open Patent Publication No. Hei 9-164162.
The quantity of pristane contained in the products of squalane is on the level that it causes almost no problem concerning the skin of healthy persons. However, because condoms are used in contact with the sensible mucous membrane, it is considered that a minute quantity of pristane may react upon the mucous membrane and it gives rise to undesirable influence of the lowering of sensibility for the mucous membrane. Furthermore, with some physical constitution of a user, there is anxiety that the user feels a pain when he suffers injuries in his mucous membrane.
Therefore, medical lubricating agent of squalane scarcely containing pristane is demanded.
In recent years, the symptom of arthritis caused by adjuvant composition has come into question and squalane is used for the adjuvant composition in place of liquid paraffin.
Examples of the uses of squalene or squalane for adjuvant compositions are disclosed in U.S. Pat. No. 5,718,904 and European Patent 0 399 843 A2. It is disclosed in these patent gazettes that squalane emulsified with an emulsifying agent was used as adjuvant, however, the pristane in the squalane was not investigated.
In recent years, there is a tendency to keep off the application of silicone oil to injection needles because the silicone oil is difficultly excreted by metabolism. It is thus proposed to use squalane in place of the former one (Japanese Laid-Open Patent Publication No. Hei 9-140790).
However, there is no instance to give consideration to the stimulative pristane.
As described above, squalane prepared from animal oil such as shark-liver oil scarcely containing pristane is demanded. It is also required that the quantity of pristane is not more than 10 wt ppm. However, this is difficultly attained through the ordinary distillation because the decomposition or other reaction takes place.